The present invention relates in general to flight suits, particularly to flying suits incorporating pneumatic bladders for applying pressure to specific areas on a person wearing the suit.
It is well known that forces resulting from aircraft maneuvers can have a pronounced effect on the blood circulation of the aircraft occupants. This effect is manifested by the "blackout" experienced by pilots of high speed military aircraft when performing banked turns or pulling out of dives. The forcing of blood away from the pilot's head at such times can temporarily cause a partial or complete loss of vision or even unconsciousness.
The foregoing problem has been addressed by numerous prior art flying suits; examples may be found in U.S. Pat. Nos. 2,379,497; 2,495,316; and 2,760,484; issued, respectively to Sellmeyer; Clark et al; and Ferwerda.
In the Sellmeyer flying suit, an inner lining and dividing webs define a plurality of air chambers surrounding the limbs and abdomen of the wearer. Air introduced at the wrists and ankles causes sequential pressurization of adjacent chambers, producing a progressive massaging effect on the wearer's circulatory system.
A similar arrangement is proposed in Clark et al; however, the design is greatly simplified, employing fewer air chambers and dispensing with the flap valves proposed by Sellmeyer. Significantly, Clark et al include bladders only at the thighs, calves and abdomen, recognizing that interruption of blood flow to the head is best stemmed by applying pressure at these points.
In Ferwerda, pressure bladders are located over the same key circulation points taught by Clark et al. A further refinement taught by Ferwerda is the use of three separate inlet conduit corresponding to the thigh, calf, and pelvic bladders. The pressure to each area is individually adjustable by means of separate pressure regulation valve means connected to each inlet conduit to the suit.
The use of separate inlet conduits to pressure chambers in a device for aiding blood circulation has been suggested for the treatment of vascular problems in general, as in U.S. Pat. No. 2,781,041, issued to Weinberg. In contrast to Ferwerda, the valving system taught by Weinberg allows control over the pressurization timing and sequencing, rather than the ultimate pressure, of each individual air chamber.
Pressurization of air bladders in prior art flying suits is typically controlled by an acceleration responsive valve which automatically opens when forces are such as may cause blackout. On long flights, however, for example with in-flight refueling, a pilot may be unable to leave his seat for extended periods of normal flight (i.e., no blackout acceleration condition). During such periods, there exists a potential for lower seated surface and lower extremity numbness due to blood pooling and unchanged pressure points. This problem has not heretofore been addressed by prior art flying suits and valving systems.